James Webb detects signs of an atmosphere on lava super-Earth HD 3167 b — ScienceDaily
Researchers have found compelling signs of an atmosphere on the rocky super-Earth HD 3167 b, located 154 light-years from Earth in the constellation Pisces. This scorching world, classified as a so-called lava planet, completes a full orbit around its star in just one Earth day, ScienceDaily reports.
The study results were published in The Astrophysical Journal Letters. The work was led by Brandon Park Coy of the University of Chicago. According to the scientists, the rocky planet's close proximity to its star should make it difficult to retain an atmosphere because of stellar wind and high-energy radiation.
How the atmosphere was detected
The team used mid-infrared data from the James Webb Space Telescope. The researchers applied the secondary eclipse method: they observed the planet passing behind its star and measured the decrease in light. This made it possible to estimate the infrared radiation from HD 3167 b and the temperature of its illuminated side.
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If the planet had no atmosphere, its dayside would heat up to the maximum possible temperature given its distance from the star and the reflectivity of its surface. An atmosphere can transport heat to the nightside, while clouds can reflect part of the star's light. The dayside of HD 3167 b proved noticeably cooler than the expected maximum, which the team considers strong evidence of an atmosphere.
The atmospheric composition has not yet been established
The illuminated side of lava planets is likely covered with molten rock. Scientists suggest that HD 3167 b may have a silicate composition similar to a mixture of minerals from Earth's mantle. It was previously believed that the atmospheres of such ultra-hot worlds could consist mainly of vaporized rock. At the same time, evidence is emerging for the possible presence of heavier gases on some lava planets, including carbon dioxide, carbon monoxide, or water. The exact composition of HD 3167 b's atmosphere remains unknown.
HD 3167 b is the coolest lava planet with known signs of an atmosphere. It became the first result of an observational program of ten ultra-hot lava worlds intended to determine whether there is a temperature threshold beyond which planets with atmospheres occur more frequently. Studying such objects may also help investigate conditions on the early Earth, when its surface may have been entirely liquid.
